Abstract: Utilizing fuzzy decording,we can mathematically transform trichromatic signals B,G,R into psycological attributes of color θ,r,z and get a quadri-chromatic space ofpsycology with some simillar properties to that of Newton's chromatic plate and amathematical model of mechanism of quadrichromatic perception.Our experiment ofcomputer discrimination of colors using the trichromatic model was quite successful.Our method proved to be simple and practical.